Evaluation of hematocrit with manually-operated centrifuge

ABSTRACT

A method of evaluating a patient&#39;s hematocrit includes collecting a sample of blood in a capillary tube, and placing the capillary tube into a centrifuge having a rotor. The centrifuge has base with a center axis and a manual rotation member. The rotor spins in response to the manual rotation member being pulled by an operator, and the rotor is coupled for rotation to the base. The rotor including a plurality of microfluidic channels. The sample of blood is separated with the centrifuge into a red blood cell portion and a plasma portion in the microfluidic channels. A diagnosis image is provided including a base line indicia, a lower normal line indicia, an upper normal line indicia and a 100 % level line indicia. The capillary tube is placed against the diagnosis image with the bottom end placed adjacent the base line indicia.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. applicationSer. No. 15/006,326 filed on Jan. 26, 2016, which is a divisionalapplication of U.S. application Ser. No. 13/858,257 filed on Apr. 8,2013, which claims the benefit of U.S. Provisional Application Ser. No.61/621,691 filed on Apr. 9, 2012, the contents of which is incorporatedby reference herein in its entirety.

BACKGROUND

The subject matter disclosed herein relates to a centrifuge and inparticular to a portable centrifuge for determining a patient'shematocrit.

Blood can be fractionated, and the different fractions of the blood canbe used to diagnose a patient to determine their medical needs. Underthe influence of gravity or centrifugal force, blood spontaneouslysediments into three layers. At equilibrium, the top low-density layeris a straw-colored clear fluid called plasma. Plasma is a water solutionof salts, metabolites, peptides, and many proteins ranging from small(insulin) to very large (complement components).

The bottom, high-density layer is a deep red viscous fluid composed ofred blood cells (erythrocytes) specialized for oxygen transport. Therelative volume of whole blood that consists of erythrocytes is calledthe hematocrit, and in normal human beings this can range from about 37%to about 52% of whole blood.

The intermediate layer is the smallest, appearing as a thin white bandabove the erythrocyte layer and below the plasma layer; this is calledthe buffy coat.

It is often desirable to check the patient's hematocrit to determine ifthe amount of red blood cells in the patient's blood is within normalranges, or if it is low (anemic) or high (polycythemic). It may bedesired to perform this analysis frequently to check the effectivenessof treatments or to determine a change in the patient's condition. Theprocessing of blood typically requires significant capital investment incentrifugation equipment, lab space and skilled personnel to process thesamples. It should be appreciated that it is often difficult to performthis analysis in areas where the local environment or infrastructuredoes not provide the economic resources for equipment or the skilledpersonnel needed to perform the analysis.

Accordingly, while existing centrifuges are suitable for their intendedpurposes the need for improvement remains, particularly in providing acentrifuge and system that can be used to check a patient's hematocritin remote or low resource areas.

BRIEF DESCRIPTION OF EMBODIMENTS OF THE INVENTION

According to one aspect of the invention, a centrifuge is provided. Thecentrifuge includes a power source, the power source configured togenerate electrical power from a renewable power source. At least onebattery is electrically coupled to the power source. A motor iselectrically coupled to at least one battery. A rotor is coupled to themotor, the rotor having a generally cylindrical body and a pair ofopposing openings opposite the motor. A pair of holders are eachdisposed in one of the pair of opposing openings, each of the holdershaving an opening on one end sized to receive a capillary tube.

According to another aspect of the invention, a diagnosis cardcomprising a base member is provided. The base member includes a baseline indicia. A lower normal line indicia is provided having a firststarting point spaced apart from the base line, the lower normal lineextending on an angle relative to the base line. An upper normal lineindicia is provided having a second starting point coincident with thefirst starting point, the upper normal line extending on an anglerelative to the lower normal line. A 100% level line indicia is providedhaving a third starting point spaced apart from the first startingpoint, the 100% level line extending on an angle relative to the uppernormal line.

According to yet another aspect of the invention, a method of evaluatinga patient's hematocrit is provided. The method includes separating asample of blood in a capillary tube into a red blood cell portion and aplasma portion, the capillary tube having a bottom end. A diagnosis cardis provided having a base line indicia. a lower normal line indicia, anupper normal line indicia and a 100% level line. The lower normal lineindicia includes a first starting point spaced apart from the base line,the lower normal line extending on an angle relative to the base line.The upper normal line indicia includes a second starting pointcoincident with the first starting point, the upper normal lineextending on an angle relative to the lower normal line. The 100% levelline indicia having a third starting point spaced apart from the firststarting point, the 100% level line extending on an angle relative tothe upper normal line. The capillary tube is placed against thediagnosis card with the bottom end placed adjacent the base line.

According to yet another aspect of the invention, a system forevaluating a patient's hematocrit in a low resource area is provided.The system includes a centrifuge. The centrifuge includes a solar panel,at least one battery electrically coupled to the solar panel, a motorelectrically coupled to at least one battery, and a rotor coupled to themotor. The rotor has a generally cylindrical body and a pair of opposingopenings opposite the motor, and a pair of holders each disposed in oneof the pair of opposing openings, each of the holders having an openingon one end sized to receive a capillary tube. The system furtherincludes a diagnosis device having a graphical screen. The diagnosisdevice being configured to display a base line indicia, a lower normalline indicia, an upper normal line indicia, and a 100% level lineindicia. The lower normal line indicia has a first starting point spacedapart from the base line, the lower normal line extending on an anglerelative to the base line. The upper normal line indicia has a secondstarting point coincident with the first starting point, the uppernormal line extending on an angle relative to the lower normal line. The100% level line indicia has a third starting point spaced apart from thefirst starting point, the 100% level line extending on an angle relativeto the upper normal line.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWING

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a centrifuge in accordance with anembodiment of the invention;

FIG. 2 is another perspective view of the centrifuge of FIG. 1;

FIG. 3 is another perspective view of the centrifuge of FIG. 1 with aportion of the housing removed;

FIGS. 4-7 are views of a rotor for use with the centrifuge of FIG. 1;

FIGS. 8A-8C are views of the rotor body of FIG. 4;

FIG. 9 is a side view of an exemplary capillary tube for use in therotor of FIG. 4;

FIG. 10 is a hematocrit card for use with the capillary tube of FIG. 9;

FIG. 11 is a top view of a centrifuge rotor having microfluidicchannels; and

FIG. 12 is a perspective view of a manually operated centrifuge for usewith the rotor of FIG. 11.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION

The monitoring of human hematocrit is desirable to diagnose a variety ofdiseases and disorders. In remote or low resource areas this may bedifficult due to the lack of facilities or economic resources to affordthe capital equipment typically used for analyzing a patient'shematocrit. Still further issues may arise in these areas in consistentcollection of a patient's sample. Embodiments of the present disclosureprovide a portable centrifuge that is capable of processing hematocritoperating under battery power or with a renewable energy source.Embodiments of the present disclosure provide advantages in the rapidprocessing of small quantities of hematocrit. Embodiments of the presentdisclosure provide advantages in the assessment of a patient'shematocrit for a range of sample volumes. Still further advantages ofthe present disclosure provide advantages in assessing a patient'shematocrit using a rotor with microfluidic channels and a manuallyoperated centrifuge.

Referring now to FIGS. 1-3, a centrifuge 20 is shown that is configuredto operate in remote areas or low resource areas. As used herein, theterm “low resource area” refers to a geographic region or area lackingconsistent or reliable access to electricity and medical laboratoryfacilities. A low resource area may also include a trauma surgeryamphitheater or a military combat theater. The centrifuge 20 has a base22 and a cover 24. The cover 24 is rotationally coupled to the base 22to allow the cover 24 to move from a closed to an open position. In theexemplary embodiment, the base 22 and cover 24 are made from a suitablylight weight material such as polystyrene or styrene butadiene methylmethacrylate for example. In one embodiment, the centrifuge 20 mayinclude an interlock switch (not shown) that prevents the operation ofthe centrifuge 20 when the cover 24 is in the open position.

It should be appreciated that while embodiments herein reference theseparation of blood with the centrifuge 20, this is for exemplarypurposes and the claimed invention should not be so limited. In otherembodiments, the centrifuge 20 may be used to separate other fluids,such as but not limited to fluids having fluid or non-fluid componentshaving different densities, tears, urine, stool, saliva, sweat, or watersources for example.

The base 22 defines a hollow area 26 arranged beneath the cover 24. Thecover 24 includes an opening that allows a shaft on a motor 30 to extendinto a space 34 within the cover 24. The motor 30 is mounted to the base22, such as with a motor mount 42 for example. The motor mount 42 may beany suitable mounting arrangement that supports the motor 30 and reducesthe transfer of vibrations from the motor 30 into the base 22. In theexemplary embodiment, the motor 30 is a 1.5-3V, 12,500 rpm directcurrent motor, such as a Model ST130-22770-38 motor manufactured byJency Motor for example. As will be discussed in more detail below, arotor 32 is coupled to the shaft and rotates within the space 34. In oneembodiment, the cover 24 is reinforced act as a containment vessel. Inyet another embodiment, the cover 24, the base 22 or the cover 24include one or more seals arrangements, such as a gasket for example,that seals the space 34 to prevent the escaping of aerosols from thecentrifuge 20 in the event a sample breaks during operation.

Disposed within the hollow area 26 may be one or more components, suchas a battery 36 and a controller 38. The battery 36 is electricallyconnected to a solar panel 40. In one embodiment, the solar panel 40 ismounted to the cover 24 opposite the space 34. In the exemplaryembodiment, the solar panel 40 is comprised of five 1000 mA, 0.55 Wsolar panels, such as a P-Maxx Series solar cell manufactured by SiliconSolar Inc for example. In one embodiment, each of the individual solarpanels 40 are 0.938 inches (23.8 millimeters) wide, 6.125 inches (155.6millimeters) long and 0.050 inches (1.27 millimeters) thick.

It should be appreciated that while a single battery 36 is shown, thisis for exemplary purposes and the claimed invention should not be solimited. The disclosed centrifuge 20 may have multiple batteriesarranged in series or in parallel. In one embodiment, the centrifuge 20has two batteries 36 that are arranged in parallel. In this embodiment,each of the batteries may support operation of the centrifugeindividually. This allows the centrifuge 20 to be operated by a firstbattery 36 while a second battery 36 is being charged by the solar panel40. In yet another embodiment, the centrifuge may be operated directlyby the power generated from solar panel 40.

It should be further appreciated that while the controller 38 is shownas a single component, the control and operation of the centrifuge 20may be performed by a plurality of individual components, each providingone or more functions, such as but not limited to a motor controller,and a battery charging circuit for example.

Referring now to FIGS. 4-8, the centrifuge rotor 32 is shown that holdshematocrit samples during operation. The rotor 32 includes a body 44 anda pair of opposing holders 46. The body 44 has a generally cylindricalshape. On a first end 48 is a threaded opening 50. The opening 50 issized and shaped to couple with a shaft on the motor 30. In theexemplary embodiment, the opening 50 has a diameter of 0.08 inches(2.032 millimeters). It should be appreciated that the motor 30 and thebody 44 may include additional features (not shown) that keep the rotor44 centered on the motor 30 shaft, such as matching conical surfaces forexample, and also include features that keep the rotor 44 fromdecoupling under deceleration, such as a pin extending perpendicular tothe shaft that is disposed within a slot on the end 48.

Opposite the end 48 is a second end 52. The second end 52 includes apair of opposing openings 54. Each of openings 54 is formed on an angleand extend through the sidewall 56 of the body 44. In the exemplaryembodiment, the openings are formed on a 65 degree angle from ahorizontal plane. In the exemplary embodiment, the openings 54 arecylindrical openings. In other embodiments, the openings 54 may havefeatures, such as a step for example, that cooperates with acorresponding feature on the holders 46 to assist in retaining holders46 in the rotor 32. In the exemplary embodiment, the body is made from apolycarbonate material, has a diameter of about 0.375 inches (9.525millimeters) and a length of 1.15 inches (29.21 millimeters).

The holders 46 are generally cylindrical in shape and having a diametersized to fit within the openings 54. The holder 46 may be made from asuitable material, such as carbon fiber for example, that is capable ofsupporting the patient's samples under the centripetal forces generatedduring operation. Each holder 46 has a first end 58 positioned distalfrom the sidewall 56. A second end 60 is opposite the first end 58. Inone embodiment, the holders 46 have a diameter of 0.125 inches (3.175millimeters) and a length of 0.9 inches (22.86 millimeters). A blindbore 62 is formed in the end 60 which has a bottom end 64 adjacent thefirst end 58. The bore 62 is sized to receive a capillary tube 66 (FIG.9). In the exemplary embodiment, the bore 62 has a diameter of 0.079inches (2 millimeters) and a length of 0.8 inches (20.32 millimeters).In one embodiment, the holders 46 are bonded to the openings 54 using asuitable adhesive such as cyanoacrylate for example.

In another embodiment, the holders 46 are gradually tapered from alarger diameter at the second end 60 to a smaller diameter at the firstend 58. The body 44 has openings 54 with a corresponding taper. In thismanner, the holders 46 may be inserted and held in place duringoperation while also allowing them to be removed for replacement orcleaning. In one embodiment, the rotor 32 is made from materials thatare suitable with chemical sterilization or autoclaving.

In operation, the centrifuge 20 is installed in a location where thesolar panel 40 is exposed to sun and the batteries 36 are charged. Itshould be appreciated that solar panel 40 may be removed from the cover24 and positioned in an environment where sunlight is available, or thecentrifuge itself may be placed in the sunlight. Once the batteries 36are charged to allow operation of the centrifuge, the clinician or othermedical personnel obtains a sample of blood from a patient in acapillary tube 66 sized to fit within the bore 62. The capillary tube 66is inserted into the centrifuge 20. Typically, two capillary tubes 66will be processed at the same time to maintain a balanced rotor 32. Inthe event that only one sample needs to be processed, the clinician mayinsert an equally weighted capillary tube with an inert material (e.g.saline) in the opposing holder 46.

With the capillary tubes 66 inserted, the cover 24 is closed and therotor is rotated for a desired period of time. In the exemplaryembodiment, the samples are processed for at a speed of 10,000 rpm for90 seconds. The rotation of the capillary tubes 66 causes the sample toseparate into a first portion 68 containing red blood cells and a secondportion 70 containing plasma. In the sample volumes used to checkhematocrit, the buffy layer while present is negligible. With the sampleseparated into its components, the clinician may then measure the height72 of the first portion 68 to determine if the patient's hematocrit iswithin the normal range, or if the patient is anemic or polycythemic.

One problem in remote and low resource areas is controlling the quantityof blood placed in the capillary tube 66. Typical conventionalhematocrit procedures simply measure the height of the red blood cellcolumn and assume that a standardized level of blood was obtained fromthe patient. As a result, the diagnosis made from reading the hematocritmay be erroneous if too large or too small of a sample is used.

In one embodiment, a diagnosis card 74 is provided that assists theclinician in diagnosing the patient by having indicia that indicatedifferent conditions. The card 74 has a series of lines, including abase line 76, a lower normal range line 78, an upper normal range line80 and a 100% level line 82. The lines 78, 80 start at a common point 84and extend on an angle, diverging as the line proceeds from the leftside of the card to the right. The diverging lines 78, 80 define thenormal range 86 of red blood cells. The 100% level line 82 starts from apoint 88 spaced apart from the point 84 and extends on an angle as theline extends from the left side to the right side. The area between theupper normal range line 80 and the plasma line 96 defines a polycythemicrange 90. Similarly, the area between the lower normal range line 78 andthe base line 76 defines the anemic range 92.

Typically, different demographics of patients will have differentdiagnosis cards. For example, an infant will not have the same normalrange as an adult. In one embodiment, the diagnosis card may haveindicia representing different demographic groups. In this embodiment,each demographic group may be differentiated by having lines ofdifferent colors. In one embodiment, the diagnosis card may includelines for an adult male, an adult female, a ten year old adolescent, aone year old child and a three month old child.

The diagnosis card 74 may be made from a suitable material for theenvironment in which it will be used, such as but not limited to paper,card stock, card board, corrugated card board, wood, plastic or metalfor example. The diagnosis card 74 may be laminated with a clearplastic. In one embodiment, the diagnosis card 74 is a graphicalrepresentation on an electronic computing device having a screen or amonitor capable of displaying the graphical representation of thediagnosis card 74, such as but not limited to a computer, a laptop, apersonal digital assistant, a tablet device, a telephone, a cellularphone, an internet phone or an e-reader device for example.

To use the diagnosis card 74, the clinician processes the capillary tube66 to separate the red blood cells from the plasma as described above.The clinician then places the capillary tube 66 against the card 74 withthe bottom 94 of the capillary tube 66 on the base line 76. Thecapillary tube 66 is then moved along the base line 76 until the plasmaline 96 intersects the 100% level line. With the capillary tube 66 inthis position, the clinician may then determine if the patient is withinnormal, anemic or polycythemic ranges. It should be appreciated that theangling of the lines 78, 80, 82 allows for scalability in the samplelevels that are processed, providing advantages in increasing theaccuracy of the diagnosis. It should further be appreciated that thediagnosis card 74, since it does not rely upon measurements with a ruleror other device, may be easier for less skilled personnel, or personneloperating in a turbulent environment (e.g. a military field hospital),to use. In one embodiment, the ranges 86, 90, 92 may be color coded tofacilitate usage to by personnel who may be illiterate or have poorreading skills.

In one embodiment, the clinician may take a digital photograph of thediagnosis card 74 with an electronic device such as but not limited to adigital camera, a cellular phone, a tablet device or a laptop forexample. The electronic computing device may then scale the photographto automatically, or through manual adjustment by the user, line up theimage of the capillary tube 66 on a graphical representation of thediagnosis card 74. In still another embodiment, the electronic computerdevice may automatically detect the level 68 and the plasma line 96 anddetermine whether the hematocrit is within the normal, anemic orpolycythemic ranges.

Referring now to FIGS. 11-12, another embodiment is shown of thecentrifuge 20 for use in low resource or remote locations. In thisembodiment, the blood sample is loaded into a rotor 100 in the form of adisk having a plurality of microfluidic channels 102, 104, 106, 108.This arrangement provides for even smaller volumes of sample from thepatient and may lead to faster separation of the red blood cells andplasma. This may provide still further advantages in having a manuallyoperated centrifuge 20 as shown in FIG. 11. In this embodiment, therotor 100 is coupled to device 110 that is similar to a yoyo having astring 112 wrapped around a center axis 114. To rotate the rotor 100,the clinician simply pulls the string 112 causing the device 110 and therotor 100 to spin. In one embodiment, the clinician may spin the rotor100 multiple times to achieve the desired separation.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

The invention claimed is:
 1. A method of evaluating a patient'shematocrit comprising: separating a sample of blood in a capillary tubeinto a red blood cell portion and a plasma portion, the capillary tubehaving a bottom end; providing a diagnosis card, the diagnosis cardcomprising: a base line indicia; a lower normal line indicia having afirst starting point spaced apart from the base line indicia, the lowernormal line indicia extending on a first angle relative to the base lineindicia; an upper normal line indicia having a second starting pointcoincident with the first starting point, the upper normal line indiciaextending on a second angle relative to the lower normal line indicia; a100% level line indicia having a third starting point spaced apart fromthe first starting point, the 100% level line indicia extending on athird angle relative to the upper normal line indicia; and placing thecapillary tube against the diagnosis card with the bottom end placedadjacent the base line indicia; wherein the separating of the sample ofblood is performed by placing the capillary tube into a centrifugehaving a rotor, the centrifuge having a base with a center axis and amanual rotation member, wherein the rotor spins in response to themanual rotation member being pulled by an operator, the rotor beingcoupled for rotation to the base, the rotor including a plurality ofmicrofluidic channels.
 2. The method of claim 1 further comprisingmoving the capillary tube until the bottom end aligns with the base lineindicia and an end of the plasma portion opposite the bottom end isaligned with the 100% level line indicia.
 3. The method of claim 2further comprising diagnosing the patient as having anemic when the endof the red blood cell portion is between the base line indicia and thelower normal line indicia.
 4. The method of claim 3 further comprisingdiagnosing the patient as having polycythemia when the end of the redblood cell portion opposite the bottom end is between the upper normalline indicia and the 100% level line indicia.
 5. A method of evaluatinga patient's hematocrit comprising: collecting a sample of blood in acapillary tube; placing the capillary tube into a centrifuge having arotor, the centrifuge having a base with a center axis and a manualrotation member, wherein the rotor spins in response to the manualrotation member being pulled by an operator, the rotor being coupled forrotation to the base, the rotor including a plurality of microfluidicchannels; separating the sample of blood with the centrifuge into a redblood cell portion and a plasma portion in the microfluidic channels;providing a diagnosis image, the diagnosis image comprising: a base lineindicia; a lower normal line indicia having a first starting pointspaced apart from the base line indicia, the lower normal line indiciaextending on a first angle relative to the base line indicia; an uppernormal line indicia having a second starting point coincident with thefirst starting point, the upper normal line indicia extending on asecond angle relative to the lower normal line indicia; a 100% levelline indicia having a third starting point spaced apart from the firststarting point, the 100% level line indicia extending on a third anglerelative to the upper normal line indicia; and placing the capillarytube against the diagnosis image with the bottom end placed adjacent thebase line indicia.
 6. The method of claim 5 further comprising movingthe capillary tube until the bottom end aligns with the base lineindicia and an end of the plasma portion opposite the bottom end isaligned with the 100% level line indicia.
 7. The method of claim 5further comprising diagnosing the patient as having anemic when the endof the red blood cell portion is between the base line indicia and thelower normal line indicia.
 8. The method of claim 5 further comprisingdiagnosing the patient as having polycythemia when the end of the redblood cell portion opposite the bottom end is between the upper normalline indicia and the 100% level line indicia.